CD4 and cancer: The fraction of CD4+ T cells expressing CTLA4 in cancer patients before seed implantation (3.01% mean with 1.38–4.63% 95% CI) was slightly higher but not significantly different from healthy controls (2.24% mean with 1.27–3.22% 95% CI), and a mild decrease was noticed after treatment, reaching significantly lower CTLA4+ T cell fractions 36 months after implantation (1.32% mean with 0.95–1.69% 95% CI) (Figure 3A).